I     ^DEPARTMENT  OF  AGRICULTURE. 

•  pf3  BDREAD  OF  PLANT  INDUSTRY  -BULLETIN- No.  63. 


INVESTIGATIONS  OF  RUSTS. 


MARK   ALFRED  CAB 
Cerealist  in  Charge  of  Cerea 


VEGETABLE    PATHOLOGICAL    AND 
INVESTIGATIONS 


[SSOED  JuiT   12,  1004. 


DOCUMEN"' 


' 


WASHINGTON: 

GO\  EURNMKNT    PRINTING    oi'ih  r;. 


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[Continued  on  page  :>  of  cover.] 


Bui  63,  Bureau  of  Plant  Industry,  U.  S  Dept  of  Agriculture. 


Plate 


A  Perennial  Rust. 
(/tciDiuM  Tuberculatum  E.&  K.on  Calurrhoe  involucrata  Gr.) 


U.  S.  DEPARTMENT  (  >F   AGRICI   I.I  URE 

BUKKM 101   PLANT  INDUSTRY     BULLETIN 


IS.    T.    I.  \  I.I.I  )\\  A  I 


NVESTIGATIONS  OK  RUSTS. 


MARK    ALFRED  CARLETON, 

(  erealist  in  Charge  of  Cereal  [nvestigations. 


'    I      .K.TABLE    PATHOLOGICAL    AND    PHYSIOLOGY 
INVESTIGATIONS. 


u  July   12,  L904. 


WASHINGTON: 

Q(  '\  ERNMENT    PRINTING    I >FFI<  H 
I  9 Or! 


BUREAU  OF  PLANT  INDUSTRY. 

B.  T.  Galloway.  Chief. 
J.  E.  Rockwell,  Editor. 

VEGETABLE   PATHOLOGICAL  AND  PHYSIOLOGICAL  INVESTIGATIONS. 

SCIENTIFIC    STAFF. 

Albert  F.  Woods,  Pathologist  and  Physiologist. 

Erwin  F.  Smith,  Pathologist  in  Charge  of  Laboratory  of  Plant  Pathology. 

George  T.  Moore,  Physiologist  in  Charge  of  Laboratory  of  Plant  Physiology. 

Herbert  J.  Webber,  Physiologist  in  Charge  of  Laboratory  of  Plant  Breeding. 

Walter  T.  Swingle,  Physiologist  in  Charge  of  Laboratory  of  Plant  Life  History. 

Newton  B.  Pierce,  Pathologist  in  Charge  of  1'acijie  Coast  Laboratory. 

M.  B.  WAITE,   Pathologist  in  Charge  of  Ineestigatious  of  Diseases  of  Orchard  Emits. 

Mark  Alfred  Carleton,  Cerealistin  Charge  of  Cereal  Investigations 

Hermann  von  Schrenk,"  In  Charge  of  Mississippi  Valley  Laboratory. 

P.  H.  Rolfs,  Pathologist  in  Charge  of  Subtropical  Laboratory. 

C.  0.  TowNSEND,  Pathologist  in  Charge  if  Sugar  fleet  [mestigatiotts. 

P.  H.  Dorsett,  Pathologist. 

Rodney  H.  Tuff.,''  Physiologist. 

T.  II.  Kearney,  Physiologist,  Plant  Breeding. 

Cornelius  L.  Shear,  Pathologist. 

William  A.  Orton,  Pathologist. 

W.  M.  Scott,  Pathologist. 

Joseph  S.  Chamberlain,  Physiological  Chemist,  Cereal  Investigations. 

II.  E.  B.  McKenney,  Physiologist. 

Flora  W.  Patterson,  Mycologist. 

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Karl  F.  Kellerman,  Assistant  in  Physiology. 

Deane  B.  Swingle,  Assistant  in  Pathology. 

A.  W.  Edson,  Scientific  Assistant,  Plant  Breeding. 

Jesse  P>.  Norton,  Assistant  in  Physiology,  Plant  Breeding. 

James  B.  Rorer,  Assistant  in  Pathology. 

Ll.oYU   S.   TENNY,   Assistant  in    I'a/hologg. 

George  <;.  Hedgcock,  Assistant  in  Pathology. 

PERLEY    SPAULDING,   Scientific  Assistant. 
I'.  J.   O'GARA,   Scientific  Assistant. 

A.  I>.  Shamel,  Scientific  Assistant,  Plant  Breeding. 

T.  Ralph  Robinson,  Scientific  Assistant,  Plant  Physiology. 

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Charles  J.  Brand,  Scientific  Assistant  in  Physiology,  Plant  Lift  History. 


a  Detailed  to  the  Bureau  of  Forestry. 

b  Detailed  to  Botanical  Investigations  and  Experiments. 


\.l\ 


fRANSMITTAL 


I        S      I  > I  I-  \  i; ;'i'\ii  \  I    i  ii     A.GKICULTURJ  . 

Bi  re  \i    of  Plant  Lndi  str^  . 

(  )ril('K    OF    THE    (    II 1K1'. 

Waxkiw/ton,  D.  <  ..  April  iO,  /!'"',. 
Sir:  I  have  the  honor  to  transmit  herewith  the  manuscript  of  ;i 
technical  paper  entitled  "Investigations  of  Rusts,"  by  .Mark  Alfred 
Carleton,  Cerealist  in  Charge  of  Cereal  Investigations,  Vegetable 
Pathological  and  Physiological  Investigations,  and  recommend  its 
publication  as  Bulletin   No.  63  of  the  series  of  this  Bureau. 

The  two  illustrations  accompanying  the  manuscript  are  neccssar}' 
to  a  complete  understanding  of  the  subject-matter  of  this  paper. 
Respectfully, 

B.  T.  Galloway, 

( 'hief  of  />'"/■' '"/. 

1  Ion.     .1  \MI .»     W  I  In  in. 

>'.  ./■,  tii,  y  ,,/ .  \.(jricultit)\ . 

3 


Digitized  by  the  Internet  Archive 
in  2013 


http://archive.org/details/investofOOunit 


PRKFACE. 


The  experiments  and  oiisciv.iii    i  nists  which  arc  the  basis  of 

the  following  notes  were  begun  by  Mr.  Carleton  several  years  ago, 
ami  ucic  continued  at  intervals  until  the  spring  of  L900,  when  the 
pressure  of  other  duties  prevented  further  work  of  this  kind  up  to 
the  presenl  time.  The  results  obtained  in  many  instances  are  slill 
incomplete,  bul  are  of  sufficient  value  to  be  recorded.  Some  of  the 
species  studied  arc  of  much  economic  importance.  The  investigation 
i-  a  continuation  of  the  work  reported  in  Bulletin  !•'>  of  the  l>i\  ision 
of  Vegetable  Physiology  and  Pathology,  and  is  concerned  chiefly  with 
the  segregation  of  rusl  forms  of  economic  importance  on  the  common 

grasses  and  tin mpletion  of  the  life  history  of  certain  species.     The 

work  is  to  be  carried  on  more  extensively  during  190-1. 

A.  P.  Woods, 
PnthoJoqixt  and  Phyxloloqixt. 
Office  of  Vegetable  Pattiologn  m    \\i> 

Physiological  Inn  esi  ig  \th  in--. 

Washington,  />.  ('.,  March  20,  W0Jh 


CONTENTS, 


!',!■'. 


Additions  to  our  knowledge  of  life  histories 

Euphorbia  rust  ( I 'rovn/eex  euphorbia?  C.  ant]  P.)  

Sunflower  rusl  i  Puecinia  helianihi  Schw.) 

Crown  rusl  of  oats    P           i  rhamni  [Pers.]  Weltst.)...   . 
Segregation  of  host  plains 

Black  stem  rust  of  Agropyron  and  Elymus 

( (range  leaf  rust  of  Agropyron  and  Klymus 

Black  stem  rust  of  Agroslis  nll><t  vulgaris 

Rusl  of  Chloris  I  Puecinia  vhlorid'ix  I  Met.  ) 

Rusts  i't'  willow  ami  cotton " 1  i  Melampsi >ra  I 

Winter  resistance  of  the  uredo 

llredo  of  Kentucky  hluegrass  rust  I  Puecinia  poarum  Niels. 

I   redo  of  Pucciiiiti  ntontanensis  Ell 

Emergency  adaptations 

Puecinia  rej'anx  Far! 

Experiments  with  Lepto-uredinere 

Rust  of  cocklebur  i  Puecinia  ranthii  Schw.  i 

Rust  of  velvet  lea      '  rospora  l">.  and  ('.  i 

Perennial  species 

/  tuberculatum  E.  and  K 

Rusl  of  Peueetlanum  fn  nieitlaceum 

Description  of  plates 


9 
9 

II 
13 
1  I 
15 
17 
17 
is 
is 
19 
20 
20 
21 
22 

26 
26 
27 
•J7 
28 
32 


I  ILLUSTRATIONS 


Page. 

Plate  I.   A  perennial  rust Frontispiece. 

II.   Rusts  of  Euphorbia  and  grama  grass. 32 

8 


K    !•    1  V.  P.  I'.  1      117. 

INVESTIGATIONS  OF  RUSTS. 


ADDITIONS    TO    OUR    KNOWLEDGE   OF    LIFE    HISTORIES. 

In  in;iii\  instances,  without  any  experimental  proof,  it  is  inferred 
thai  there  is  a  connection  between  the  different  forms  of  rust  occur- 
ring on  the  same  hosl  plant  simply  because  of  their  constant  associa- 
tion with  each  other.  Sometimes  it  is  afterwards  demonstrated  that 
these  inferences  are  wrong,  though  they  are  probably  correct  in  a 
majority  of  cases.  Studies  of  the  following  species  were  made  with 
the  \  iew  of  obtaining  a  more  accurate  knowledge  of  their  life  history. 

El  phorbla   Rust  {Uromi/ces  euphorhia  ( '.  and  P.). 

Until  the  experiments  herein  described  were  performed  it   hail  not 

been  del istrated  that   there  is  am  connection   between  the  svcidial 

and  other  stages  of  this  species,  although  experience  naturally  leads 
one  to  think  that  there  i-.  They  are  in  very  close  association  on  the 
same  plant,  the  jecidium  appearing  first,  quickly  followed  by  the 
uredospores.  In  the  spring  of  L893  Mr.  J.  B.  S.  Norton,  now  pro- 
fessor of  botany  at  the  Maryland  Agricultural  College,  while  engaged 
in  experiments  in  the  germination  of  weed.-  in  the  greenhouses  of  the 
Agricultural  Experiment  Station  at  Manhattan.  Kan-.,  called  the 
w  liter'-  attention  to  a  very  young  rusted  seedling  of  Euphorhia  </<  ntata. 
In  this  instance,  as  is  usually  the  case  with  the  3'oung  plants  of  this 
host,  the  pod-  were  first  badly  affected  by  secidia.  This  fact,  taken 
together  with  the  common  observation  that  the  seed  pods  of  this  host 
are  usually  affected  by  all  stages  of  the  rust,  lei  I  at  once  to  the  thought 
t  hat  it  was  a  case  of  rusl  propagation  through  the  medium  of  the  germi- 
nating seed  of  the  host,  something  not  before  demonstrated  for  any 
other  -peri,-  in  the  entire  group  of  Uredinese,  so  far  a-  the  writer 
know-,  unless  we  except  the  single  instance  of  the  experiment-  of 
Doctor  Eriksson    with  Puccini  a  ghimaruin.b    The  seed  used  by  Mr. 


a  Vie  latente  et   plasmatic)  ue  <le  certaines  Uredin£es.     (' pi.   Rend.,   1897,  pp. 

177. 
'<  T.  s.  Ralph,  in  Victorian  Naturalist,  Vol.  VII,  p.  18,  describes  an  instance  of  a 
rust  attacking  the  seed  of   s  stating  thai   "  with  the  microscope  we  are 

able  to  trace  the  fine  yellow  sporular  mallei-  into  the  covering  of  the  seed,  and  into 
the  seed  itself;"  but  apparently  it  was  not  determined  by  further  investigation 
whether  or  nol  the  rusl  was  able  to  reproduce  itself  through  the  germinating 

9 


10  INVESTIGATIONS    OF    BUSTS. 

Norton  was  examined  and  the  pods  were  found  to  be  badly  affected. 
Moreover,  he  stated  that  the  seeds  were  planted  without  shelling.  But 
the  writer  did  not  know  then,  as  he  does  now.  that  this  fact  would 
probably  make  little  difference,  since  the  naked  seeds  are  commonly 
affected,  often  showing  actual  peridia. 

To  test  the  theory  of  rust  propagation  above  mentioned,  experiments 
were  instituted  on  April  22  for  growing  plants  from  rusted  seed  under 
a  bell  jar.  The  seed  used  bore  all  stages  of  the.  rust.  The  experiments 
were  in  live  series:  (1)  Seeds  shelled  and  disinfected  by  mercuric 
chlorid;  (2)  seeds  unshelled  and  disinfected;  (3)  seeds  shelled,  but  not 
disinfected;  (1)  seeds  unshelled.  not  disinfected;  (."»)  like  series  No.  -f, 
but  rusted  mainly  with  secidium.  All  were  planted  in  pots  in  a 
greenhouse  and  the  pots  were  kept  under  bell  jars.  On  May  L  the 
plants  began  to  come  up.  After  about  three  months,  when  the  plants 
had  grown  to  a  height  of  3  to  5  inches,  no  rust  had  appeared  on  series 
1  and  -J,  and  only  one  spot  on  one  plant  of  series  3.  The  plains  of 
series  4  and  5  were  much  rusted,  the  secidium  appearing  first,  fol- 
lowed shortly  by  uredosori. 

On  April  25,  1893,  it  was  attempted  to  germinate  teleutospores  of 
rust  from  the  seeds  used  in  these  experiments,  in  water-drop  cultures, 
which  resulted  in  failure.  On  June  28,  1893,  a  similar  culture  of  the 
fresh  uredospores  failed  to  germinate  in  two  days. 

In  1895  rusted  seeds  of  Euphorbia  <A  ntata,  sent  from  Kansas,  were 
planted  in  the  greenhouse  of  the  Department  of  Agriculture,  at  Wash- 
ington, I).  C.  From  these  three  plants  grew,  which  were  kept  under 
a  bell  jar.  Soon  one  of  these  plants  rusted  badly,  first  with  the  secid- 
ium, then  a  slight  amount  of  the  uredospores,  and  later  the  teleuto- 
spores. It  should  lie  remarked  here  that  Kuphorbia  rust,  so  far  as 
reported,  occurs  only  on  K.  maculata  in  the  vicinity  of  Washington, 
D.  C.,and  the  writer  has  never  vet  been  able  to  obtain  rusted  seeds  in 
that  region. 

On  December  11,  1896,  a  third  series  of  experiments  was  started  at 
Washington,  D.  C.  On  that  date  rusted  seeds  of  Euphorbia  </>  ///i/f>/ 
from  Kingman  and  Manhattan.  Kans.,  were  planted  and  kept  under  a 
bell  jar  as  before.  Eleven  plants  resulted  by  December  26.  On  March 
8,  1897,  spermogonia  appeared  in  considerable  amount  on  the  young 
leaves  of  one  plant,  with  a   tendency  to   form  a  sort   of  hexenbesen. 

On  March  2i»  two  more  plants  were  rusted,  one  with  spermogonia 
only  on  the  young  leaves,  and  the  other  with  iccidia  on  the  fruit. 
On  April  lo  still  another  plant  showed  spermogonia,  making  four  in 
all,  out  of  the  eleven,  that  became  rusted.      (See  PL  II.  tig.   1.) 

As  above  stated,  the  proof  that  the  rust  actually  penetrates  the  hulled 
seed  is  readily  obtained,  not  only  from  microscopical  demonstration, 
but  also  from  the  fact  that  the  actual  peridia  may  often  be  seen  with 
the  unaided   eye  in   the  seed.     These  experiments,  however,   further 


-I   NFLOWEE    RUST.  1  1 

demonstrate  the  ability  of  the  nisi  to  propagate  itself  through  the 
medium  of  the  germinating  seed  of  the  host,  and  also  make  it  seem 
probable  thai  this  is  even  the  sommon  method  of  reproduction  in  the 
case  "l  it-  occurrence  <>n  Euphorbia  dentata. 

It  will  lir  noted  also  thai  the  results  of  these  experiments  make  it 
almost  certain  thai  the  /Ecidium  and  LTromyces  appearing  upon  the 
plants  are  "in-  and  the  same  species,  since  in  every  case  all  stages 
resulted  from  planting  the  rusted  seeds,  the  secidium  appearing  first, 
then  tin'  uredo,  ami  then  the  teleutospores.  If  anything  was  lacking, 
however,  the  proof  lias  since  been  made  complete  by  the  experiments 
of  Dr.  .1.  ( '.  Arthur,  as  reported  in  tin*  Botanical  Gazette,"  in  which 
the  uredospores  and  teleutospores  were  obtained  on  Euphorbia  nutans 
from  a  sowing  of  secidiospores  from  other  plant-  of  the  same  host  on 
June  20,  L899. 

A.s  is  well  known,  the  Euphorbia  rust  is  widelj  distributed  overthe 
United  States,  occurring  on  numerous  host  species,  but  it  is  probably 
mostabundant  on  E.  dentata  and  E.  preslii.  It  is  a  significant  fact. 
bearing  upon  the  ontogeny  of  the  species,  that  it  i-  also  on  these  two 
hosts,  particularly  on  /•.'.  dentata,  that  the  aecidium  is  most  common, 
and  that  tin'  rusl  attack-  the  seed  so  severely.  The  seed  pods  arc  also 
affected  considerably  in  the  cases  of  A',  lata  and  /:'.  rnargi nata. 

On  June  12,  L897,  tecidiospores  of  this  rust  had  germinated  very 
well  in  water  drop  culture  after  three  days,  and  on  June  'I'l.  after  a 
two  days'  culture  in  water  of  both  the  tecidium  and  uredo  from 
Euphwbia  marginata^  the  latter  germinated  sparingly,  but  the  former 
not  at  all.  In  no  instance  could  the  teleutospores  be  germinated, 
though  germination  was  not  attempted  \w\  often. 

The  writer  has  collected  all  three  stages  of  this  nist  on  Euphorbia 

[data,  A',  marginata,  I:',  dentata,  /'.'.  preslii,  E.  glyptosperma,  and 

'•.'.  hettvophylla.     On  E.  jpetaloidea  and  E.  seipyllifolia  only  the  uredo 

and  teleuto  stages  were  found,  and  on  /*.'.  lata  and  what  was  probably 

A',  geyeri  even  the  uredo  was  rarely  seen. 

Si  m  lower   Rust  {Puccinia  helianthi  Scuw.  i. 

Although  Saccardo  rightly  regards  this  species  of  Schweinitz  as 
quite  distinct,  and  includes  with  it  the  ^Ecidium  often  associated  on  the 
9ame  host,  in  many  herbaria  the  authority  of  Winter  and  Burrill  is 
followedin  making  it  a  form  of  Puccinia  ta?iaceti,  while  the  ^Ecidlum 
i-  commonly  referred  to  .  K'nli n m  compositarum,  a  convenient  dump 
ing  ground  for  numerous  uncertain  forms.  The  writer  has  always 
considered  this  disposition  >>\  the  species  to  he  without  any  good 
rca- \cn  on  a  purely  morphological  basis, and  now  the  experiments 

Utliur.  .I.C..  "Cultures  of  Uredinwv  in   1899,"  Bot    Gaz  ,  Vol    \\l\.  No.  I. 
pp.  270-271,  April,  L900. 


12  INVESTIGATIONS    OF    RUSTS. 

here  recorded  make  it  rather  certain  that  Schweinitz  and  Saccardo  are 
correct.  So  far  as  this  country  is  concerned,  the  writer  is  convinced 
that  P.  tanaceti  either  belongs  almost  entirely  to  tanacetum  or  does 
not  exist  at  all.  So  far  it  has  been  utterly  impossible,  even  in  a  green- 
house, to  make  transfers  of  the  uredo  from  one  to  another  of  the 
numerous  supposed  hosts  of  that  species,  except  among  hosts  of  the 
same  genus."  It  is,  at  any  rate,  pretty  certain  that  the  forms  occurring 
on  Vernonia,  Helianthus,  Actinella,  and  Aplopappus,  which  have  been 
referred  to  /'.  tanaceti  at  various  times,  should  he  considered  distinct. 

The  circumstances  connected  with  the  culture  experiments  with  this 
species  were  in  themselves  peculiar.  Late  in  the  autumn  of  1897  at 
Manhattan.  Kans.,  it  was  desired  to  obtain  fresh  material  of  the  uredo 
for  inoculating  various  hosts,  but  at  that  date  very  little  else  than  the 
teleuto  stage  could  be  found.  Finally,  on  October  '2U  a  small  amount 
was  found  on  Helianthus  petiolaris,  mixed  among  a  much  larger  quan- 
tity of  teleutospores,  and  from  this  material  sowings  were  made  on  //. 
petiolaris  and  //.  annuus.  On  November  8  there  resulted  one  rust  spot 
on  the  latter  host  and  three  on  the  former.  The  spots  were  of  the 
uredo  stage,  but  the  interesting  feature  accompanying  this  culture  was 
the  appearance  first  of  spermogonia  in  one  of  the  spots.  This  fact 
made  it  probable  that  a  part  of  the  infection  resulted  from  the  teleuto- 
spores of  the  inoculating  material,  even  at  this  unusual  season  for  the 
germination  of  these  spores.  On  March  7,  1898,  while  stationed  at 
the  University  of  Nebraska,  inoculations  of  //.  petiolaris  were  again 
made  with  the  teleutospores  only  from  other  plant-,  of  the  same  host, 
from  which  numerous  spermogonia  appeared  in  eight  days,  followed 
shortly  by  eecidia,  which  were  fully  developed  by  November  1.  By 
these  results  the  connection  of  the  different  stages  of  the  rust  is  pretty 
well  established.  At  the  same  time  it  is  shown  that  the  forms  on 
//.  petiolaris  and  //.  annuus  are  identical.  In  all  cultures  made  of 
this  rust  both  the  uredospores  and  teleutospores  have  been  found  to 
germinate  easily  and  produce  infections  readily.  Reverse  cultures 
with  secidiospores  were  not  made. 

These  experiments  were  first  reported  at  the  L900  meeting  of  the 
Society  for  Plant  Morphology  and  Physiology,  at  Baltimore.  Since 
that  time  Drs.  .1.  C.  Arthur''  and  W.  A.  Kellennan'  have  made  a 
number  of  such  experiment-,  confirming  these  results,  bul  also  seem- 
ing to  indicate  a  distinction  of   host  forms  on  different  species  of  sun- 


"Dr.  M.  Voroninat  first  also  obtained  negative  results  in  similar  experiments  in 
Russia  in  attempting  transfers  of  the  rust  on  to  other  hosts.  (See  Bot.  Zeitung,  vol. 
30,  pp.  (>w4  698,  Sept.  27,  L872.)  Later  he  obtained  infections  of  Puccinia  tanaceti 
from  Tanacetum  vulgare  on  sunflower,  which,  however,  did  not  produce  such  vigorous 
gro^  ih  as  ordinarily.     (Bot.  Zeitung,  vol.  '■'<■>,  pp.  340,341,  May  II,  ls7">.  i 

^Botanical  Gazette,  vol.  35,  p.  17,  January,  L903;  Journal  of  Mycology,  vol.  lit, 
pp.  12  l:;,  January,  L904. 

c  Journal  of  Mycology,  vol.  9,  pp.  230-2.".2,  December,  1903. 


(  i;m\\n    ki  -  i    OF   0  VTS.  1  3 

flower.  Doctor  Voronin,  in  bis  experiments  above  mentioned,  also 
found  thai  rusl  of  cultivated  sunflower  would  not  infect  Tlelianthm 
tiil>,  rosus.  In  l'.'oi  Ernst  Jacky  "  inoculated  the  following  hosts  with 
teleutospores  from  Tlelianthm  tinnitus:  II.  annum,  II.  citcumerifolim, 
II.  call '/ ',,/■/, I, us,  II.  tuber/mis,  II.  maximiliana,  II.  mitftijforus,  II. 
scaberi/n us,  and  //.  rigidus,  with  resulting  infections  of  the  three  first- 
named  species,  but  no  infection  of  an\  of  the  others. 

The  evidence  from  all  these  experiments  jusi  quoted  and  those  of 
the  writer  shows  at  leasl  that  the  rusts  of  Tlelianthm  annum  (includ- 
ing cultivated  varieties),  //.  petiolaris,  and  //.  mollis  are  identical. 
with  the  probability  thai  a  distinct  form  exists  <>n  //.  tuberosum. 

Sunflower  rusl  has  been  collected  by  the  writer  on  the  following 
species  of  rlelianthus,  including  all  stages  on  nearly  every  species: 
//.  annum  (both  wild  and  cultivated),  //.  rig  id  as,  II.  petiolaris,  II. 
tuberosus,  II.  hirsutus,  Il.niaxuniliana-,  II.  grosse-sewatus,  II.  orgyaltx, 
II.  mollis,  and  //.  ciliaris.  The  secidium  occurs  rarely  in  compari 
son  with  the  occurrence  of  other  stages,  but  is  to  be  found  on  a  num- 
ber of  hosts  and  occasionally  in  considerable  abundance.  This  rarity 
of  it-  occurrence,  together  with  the  occurrence  of  spermogonia  so 
often  with  the  uredo,  ma\  be  accounted  for  by  the  fact  that  the  uredo 
is  often  produced  by  direct  teleutosporic  infection. 

Crown   Rust  of  Oats  (Puccinia  rliamni  [Pers.]  Wettst.). 

In  a  mere  note  in  a  previous  bulletin  of  this  Department4  it  is  stated 
that  certain  infection-  had  just  been  made  showing  the  connection  of 
the  crown  rust  of  oats  on  Phalaris  caroliniana  and  Arrhenatheruni 
elatius  with  the  recidial  form  on  Rhamnus  lanceolata.  No  other  dem- 
onstration of  such  a  connection  of  form-  had  been  reported  up  to  that 
time.  During  the  same  season,  however,  Doctor  Arthur  obtained 
infections  with  the  (ecidium  of  Rhamnus  lanceolata  on  out-  at  Lafayette, 
lnd.      The  experiments  of  the  writer  are  here  given  in  detail. 

On  August  23,  L897,  the  uredo  stage  of  a  rust,  supposed  to  be  / 
cinia  coronata,  was  found  in  great  abundance  on  Phalaris  Carolinian 
at  Stillwater,  ( >kla.  This  host,  with  the  rust,  was  transferred  to  a  green- 
house of  the  Agricultural  College  at  Manhattan.  Kan-.,  and  inocula- 
tions were  made  on  oats,  wheat,  and  orchard  grass  on  August  30,  L897, 
resulting  September  7  in  a  good  infection  of  oats,  a  poor  one  of  the 
orchard  grass,  and  no  infection  at  all  of  wheat.  Other  inoculations 
were  made  September  1  on  wheat  and  rye,  with  no  result.  By  October 
8  the   teleutospores   had  appeai'ed  on  the  original  plant-  of  Phalaris 

I     .iirall..  Bakt.  Parasit.  u.  Infekt,  2  Vbt.,  Bd.  9,  No.  21,  pp 
1902. 

I  ereal  Rusts  of  the  United  States,  Bui.   So.   I(>,  [)iv.  of  Veg.  Phys.  and   Path., 
1     -    Dept.  of  Agriculture,  1899. 
■  Bui,  Lab,  Nat.  Hist.  State  Univ.  Iowa,  Vol.  IV,  p]  i,  December,  L898, 


lic- 
et 


14  INVESTIGATIONS    OF    RUSTS. 

at  Stillwater  and  were  of  the  crown  rust  type.  After  this  date  the 
experiments  were  continued  at  the  State  University  laboratories  at 
Lincoln,  Nebr.,  all  host  plants  then  in  use  being  transferred  to  that 
place.  On  November  L<>  the  crown  rust  was  found,  in  the  uredo  stage, 
on  Arrhenatherum  <  hit  ins  on  the  State  University  farm,  and  a  rusted 
plant  was  transferred  to  the  greenhouse.  On  December  11  inoculations 
with  the  rust  were  made  on  oats  and  rye,  resulting  in  a  good  infection 
of  the  former  in  twelve  days,  but  with  no  result  on  the  latter.  Fur- 
ther inoculations  of  oats  with  the  Phalaris  rust  on  February  IB,  1898, 
resulted  again  in  a  good  infection  in  9  days. 

No  species  of  Rhamnus  is  native  near  Lincoln.  Nebr.,  but  Rhamnus 
lanceolata  is  rather  common  at  Weeping  Water,  about  20  miles  east  of 
Lincoln,  where  it  is  often  badly  rusted  with  .ZEcidium.  From  that 
place  a  large  amount  of  the  .Fcidiuin  was  obtained  fresh  on  -June  1, 
1898.  A  water-drop  culture  of  the  material,  made  the  next  day,  gave 
a  profuse  germination  of  the  spores  in  twenty-two  hours.  Inocula- 
tions with  the  a'cidiospores  on  oats  and  Phalaris  caroli/niana  were 
made  .June  1  and  June  2,  resulting  in  a  successful  infection  of  Phalaris 
on  June  14  and  of  oats  on  June  18.  The  oat  inoculations  were  made 
simply  on  detached  portions  of  the  plant  preserved  with  their  broken 
ends  in  water  in  a  damp  chamber.  As  in  all  other  instances,  these 
inoculations  were  made  with  the  greatest  of  care  to  prevent  accidental 
infections.  The  whole  series  of  experiments  proves  (1)  the  connection 
of  the  secidial  form  of  Rhamnus  with  the  crown  rust  of  oats,  and  (2)  the 
identity  of  the  latter  with  the  forms  on  Phalaris  caroliniana  and 
Arrhenatherum  elatius,  besides  making  it  probable  that  orchard  grass 
may  also  support  this  species. 

SEGREGATION  OF   HOST   PLANTS. 

The  most  important  economic  results  of  the  study  of  rusts  are  likely 
to  be  derived  from  the  investigation  of  the  relationship  of  the  forms  on 
our  common  grasses.  Such  work  has  already  been  carried  on  to  some 
extent  by  the  writer  and  partially  reported  in  the  bulletin  entitled 
"Cereal  Rusts  of  the  United  States."  A  more  detailed  account  of 
some  of  this  work  will  be  given  here.  Because  bearing  upon  the  same 
question,  it  seems  proper  to  mention  also  some  experiments  with  the 
rusts  of  Salix  and  Populus.  Probably  the  greatest  confusion  exists 
concerning  the  identity  of  the  different  forms  on  Agropyron  and 
Kl yinus,  though  there  is  much  uncertainty  also  about  those  occurring 
on  Bromus  and  other  genera. 

The  experiments  here  described  were  conducted  at  Stillwater,  Okla., 
Manhattan.  Fans..  Lincoln,  Nebr.,  and  Washington,  D.  C,  the  host 
plants  being  sometimes  transferred  from  one  place  to  another.  Of  all 
these  rusts  the  one  receiving  most  attention  was  the  black  stem  rust 
of  Agropyron  and  Flymus. 


ltl.ACK    STEM     RUST    OF     AGROPYRON     \NI»    ELYMUS. 


L5 


Bla('k  Stem   K'i  si   ok  Agropyron    wi>  Elymus. 

At  least  three  and  probably  four  ditferenl  rust*!  occur  on  the  species 
of  these  two  grass  genera,  and  are  often  so  closely  associated  tha( 
their  accurate  identification  is  extremely  difficult.  Of  the  herbarium 
specimens  of  these  rusts  throughout  the  country,  probably  not  one  in 
fifty  is  identified  with  any  certaint}'.  The  writer's  experiments  with 
these  forms  are  -till  incomplete,  bul  a  few  things  at  leasl  have  been 
established.  When  these  grasses  are  brought  under  cultivation  the 
changed  conditions  and  proximity  to  other  grasses  and  grains  cause 
them  in  become  much  more  rusted  than  is  ordinarily  the  case.  In 
the  cultivated  grass  plats  at  the  experiment  stations  in  Oklahoma, 
Kansas,  and  Nebraska  the  rusts  were  found  in  great  abundance.  It 
was  therefore  easy  to  carry  on  many  culture  experiments.  These 
experiments  with  the  uredospores  of  Mack  stem  rust  were  sufficiently 
numerous  to  make  it  desirable  to  arrange  them  in  the  follow  ing  table: 

Taui      I       I  ultun  experiments  with  black  stem  rust  of  Agropyron  and  Elymus. 


Date. 


Origin  of  inoculating 
material. 


Washington,  D.C.    Wheat. 

Do     do  do. 

Jan  22, 1897 do do  . 

I '•■ do do  . 


Do do 

Do do 

Sept.  13  L89  Stillwater, Okla  ... 

Do do 

...    Manhattan,  Kans  . 
Do do 

Do do 

Do do 

Oct.  21, 1897 do 

Do do 

Do do 

Do  do 

I". do 

Do do 

Do      do 

Do do 

1,1897  ...    Lincoln, Nebr 

Jan.5,  1898 do 


....do 

...  do 

Agropyron  U  nt  rum .. 


mini. 

do 


do 

Jan. 21,  ls'.i-> do 


Do 

I      i    11,  1898 


Do. 
Do 
Do 
Do 


Di 


Do. 


.do. 
.do. 

.do. 
.do. 
.do. 
.do. 

.do. 
.do. 

.do. 
.do. 
.do  . 


Agropyron  occ 
Wheal      (originally 

do 

.I.. 

do 

do 

do 

do 

Agropyron  occidi  ntale 
clci 

do 

do 

.do 

Elymus     in  mull  nsU 
folius. 

do 

Wheal      (originally 

I'.hllh 

.do 

I\l  l/lll  Il- 
l/Ill III  i  ! 

.....do  

do 


riant  inoculated. 


Elymus  virgii  ■ 

Wheal 

Elymus  I'irginicus 

Agropyron     richard- 
soni. 

Wheat 

Agropyron  occidi  ntale 

Wheal 

Agropyron  tt  m 

Wheal 

do 


Hurley 

Agropyron  tcnerum  . . 

w  heal 

Barley 



Rye 

Wheal 

Rye 

Barley 

Agropyron  I*  m  rum  . . 
Af/ropi/ron  occidi  utali 
Wheat 


Barlev. 
Wheal . 


.do  . 
.do. 

.do  . 
.do. 
.do  . 


Barlev 

Rye 



Elymus     cumuli  n*is 

glaucifolius. 
Elymus 
Elymus  virgi  n  icu s 

muticus. 
Elymus  inli  rmedius. . 

■  hi  li  in  mm  . . 


Result. 


Success, 
Do. 
Do. 

Do. 
Failure. 
Succi 

1  ><.. 
Failure. 
Success. 

Failure.  <■ 
Success; 

Do. 
(rf) 
Kiii  hi  re. 

Do 

Do. 

Do. 

Do 
Success. 

Do.« 

I  >". 
Do, 


Do. 

II  Do./ 

II  Do 

1 1  Failure. 

ll  Do. 

II  Mi 

ll  Failure. 

II  Do. 

II  Do. 

II  I  >n. 

II  Do. 


a  Pustules  differ  in  color  from  the  original. 
'■l  pustule  only. 

i  itions  \  cry  unfavorable,  li"» 


d  Apparently  l  pustule  fonm 

•  Rusi  changes  color  and  form  of  pustule. 

'  RusI  changes  color. 


16  INVESTIGATIONS    OF    RUSTS. 

Table  I.  —  Culiun  <  vp<  rirm  nls  iirith  black  stem  rust  <■/ .  [gropyron  and  Elymus— (  lontinued. 


Date. 

Locality. 

i  >rigin  of  inoculating 

material. 

Plant  inoculal ion. 

Period 
of  incu- 
bation 

in  daj  - 

Result. 

Feb.  11,  1898.... 

lie, 

Lincoln,  Nebr 

.1.. 

Elymus  virgirt 
do 

K/ii  mux    virgin  icus 

lllllli,   ll>'_ 

Elymus     canadensis 

glaucifolius. 
Agropyron  U  nerum. .. 
Agropyron     occidi  n- 

tali 
Rye 

13 
13 

13 

13 

13 

13 
13 

7 

11 
'J 

Sllcce-s. 

Do 

1 1,1 

do 

do... 

1  10 

Do 

do 

do 

Do 

Do 

do 

...do 

Ho 

do 

do 

Do 

Do 

do 

do 

Wheat . . 

Do 

Feb.  21,  1898 

do 

Wheal      (originally 
Elymus  canadi  nsii 
glaucifolius). 
do 

Elymus  canadensis. . . 

Hordt  a  in  jubat 
Wheat .. 

Do 

Feb.  28, 1898 

do 

Elymus     cana 
ijlaucifolius 

Do  b 

a  Pustules  differ  in  color  from  the  original. 


''Knst  changes  in  appearance. 


The  results  of  these  experiments,  considered  in  connection  with  those 
recorded  in  Bulletin  No.  16,  Division  of  Vegetable  Physiology  and 
Pathology,  U.  S.  Department  of  Agriculture,  appear  to  establish  two 
things,  viz,  (1)  that  the  forms  of  black  stem  rust  on  wheat,  barley, 
Ilordeum  jubatum,  Agropyron  t,  m  rmn,  A.  richardso?ii,  Elymus  cana- 
densis, and  E.  cancul< ns'ix  glaucifolius  are  identical,  with  the  proba- 
bility that  those  on  Elymus  virginicus,  /:'.  virginicus  muticus,  and 
Holcus  lanatus0  should  lie  included;  (2)  that  the  black  stem  rust  of 
Agropyron  occidentaleb  is  physiologically  distinct  from  any  other.' 

A  very  interesting  phenomenon  in  these  experiments  was  the  change 
in  color  and  form  of  sorus  of  the  rust  produced  by  a  transference  to 
another  host.  Jn  some  eases  after  a  transfer  the  rust  was  scarcely  recog- 
nized. The  change  of  color  was  sometimes  from  a  bright  yellow  to  a 
deep  brown  or  orange,  or  the  reverse.  The  uredo  of  Agropyron  /i/i<- 
riim.  for  example,  was  often  very  yellow  on  the  leaves,  but  changed  to 
brown  when  transferred  to  wheat.  On  the  specie- of  Elymus  the  rust 
has  a  brown,  waxy  appearance,  and  the  teleutospores  long  remain  cov- 
ered by  the  epidermis  of  the  host. 

"On  January  5,  L900,  quite  successful  infections  <>n  wheal  were  made  with  the 
uredospores  id'  black  stem  nisi  of  this  host. 

&  Probably  the  most  correct  name  of  this  host,  which  is  known  also  as    [gropyron 

spicatum  and  A.  glaucui        (Sec  Hitchcock,  "Note  on  X mclature,"  Science,  vol. 

17,  pp.  827-828,  May  22,     (03. ) 

'The  form  mi  this  host  was  described  as  a  distinct  species,  named  Pttcciniaagrojryri, 
by  Ellisand  Everhart,  in  Journal  of  Mycology,  Vol.  VII,  p.  131,  March  Hi.  1892,  a 
lad  nut  noticed  by  the  writer  until  alter  must  of  these  experiments  were  made. 
This  species  includes  iridium  clematidis  l>.  C.  according  to  Doctor  Dietel,  the  proof 
of  relationship  being  the  resultof  culture  experiments.  (Oesterr.  Bot.  Zeitschr., 
No.  8,  1892.) 


OK  V.NG  I      1.1    \l      Ki  ST    OF    AOKOl'}  RON      \M> 


,YMI 


17 


Oranoe  Leaf  Liusi   oi    Aoropyron    \m»  Elymus. 

In  the  following  table  are  summarized  the  results  of  inoculation* 
with  the  uredoform  of  this  rust.  Thej  were  carried  on  simultaneous! y 
with  those  of  the  Muck  stem  rust,  and  the  material  was  taken  chiefly 
from  the  same  individual  host  plants. 

Table  II.  -  Culture  experiments  uith  on  st  of  Ayropijron  and  i        i    • 


Locality. 

i  irigin  of  inoculating 
material. 

Kyi- 

I'lanl  inoci 

Period 
liatioii 

I;. -mi 

1896. . . 

Washingl !>.(' . . 

do 

1 
live.... 

111 

13 

18 

18 
18 
12 
12 

26 

9 

21 
21 
18 
18 

1  1 
1  1 
11 

1  1 

|>o 

do 

do 

do 

Jan.  7,  IS97 

Llo   

do 

do 

HI  il  in  ut 

Fl -Ii.  1,  \K>~..  . 

..do. 

do 

Rve 

...do 

...(In 

1 

..:tlo    . 

Wheal 

Agropyi 

Wheal 

Rye 

1 
/ 
Rye 

Do 

do 

do 



1897.... 

Do 

Ho 

do 

iln 

do 

do 

do 

(In 

Manhattan,  Kuns 

do 

do 

Rye  

do 

do    

Do 
Do. 

....do 

0   1897 

....do 

Agropyi  on 
Rye 

do 

do 



s 

Do 

do 



Do. 

....do 

do 

Agropyron  /• 

Do. 



do 

do 

do 



Jan.  ■">,  1898  . . . 



do 

Do. 

Do.. 

....do 

...do 

Wheat 

Failure 

M;ir.  1 

do 

niciis 

/ 

Wheat  ' 

Do. 

Do.. 

do 

Do. 

Mar.  1. 

..do     . 



do 



do 

Elymu*  eanadt  nsis  . .. 

Failure 

Hn..._ 

do 

do 

do    

Do 

Do <1o 

Do 

The  chief  conclusion  to  lie  derived  from  the  results  of  these  cultures 
is  that  the  orange  leaf  rust  is  very  sharply  limited  in  it-  hosl  adap- 
tation and  differs  widely  in  this  respect  from  the  black  stem  rust. 
Similar  results  are  given  in  Bulletin  No.  1*''  of  the  Division  of  Vege- 
table Physiolog3  and  Pathology,  I'.  S.  Department  of  Agriculture, 
for  cultures  of  the  form-  on  wheal  and  rye.  In  fact,  it  is  quite  proba- 
ble thai  almost  every  distinct  host  species  bears  a  distinct  form  of  the 
rust.  One  of  these  forms  on  Elytnvs  virginicus  L.  has  recently  been 
found  1>\  Doctor  Arthur  to  be  connected  with  the  .Kcidimii  on  Impa- 
tiens  aureu  Muhl.  and  is  now  to  be  known  as  Puccinla  imjwtivntU 
(Schw.)  Arth.  ' 

Black   Stem   Ki  - i   of    Vorostis   vera  vulgaris. 


Culture  experiments  with  the  uredoform  of  this  rusl  and  observa- 
tions in  the  lie  Id  indicate  that  it  is  distinct  and  doe-  not  occur  on  other 


tanical  Gazette,  vol.  35,  pp.  Is  19,  January,  1903. 
l'77s:     No.  63—04 2 


INVESTIGATIONS    OF    RUSTS. 


hosts."    The  results  of  the  culture  experiments  are  given  in  the  follow- 
ing table: 

Table  III.  —  Culture  experiments  with  black  stem  rust  of  Agrostis  alba  vulgaris. 


Date. 

Locality. 

Origin  of  inoculating 

material. 

riant  inoculated. 

Pel  iod 
■  it  incu- 
bation 

in  days. 

Result. 

Dec.  23,  1897... 

Do 

Lincoln.  Nebr 

do 

Agrostisalba  vulgaris. 
do 

Ag rostis  alba  vulgaris. 

Wheal '. 

Oats 

s 

8 
s 
12 
12 

11 

Success. 

Do... 

....do •. 

do 

I'd 

Jan.  24,  1898... 

...do. 

...do  . 

Wheat . 

Do 

Do 

....do 

...do.... 

Oats 

Do 

.Feb.  11,  1898... 

.do. 

Elymus     canacU  nsis 
glaueifolius. 

Ag  ostii  alba  vulgaris. 

Do. 

The  rust  is  evidently  of  the  black  stem  rust  group  {Puccinia  graminis 
of  authors),  but  contains  quite  a  number  of  abnormal  teleutospores, 
including  mesospores.  Many  measurements  of  these  spores  average 
27-5i  by  16-23yu,  mostly  40^6  by  16-18/*. 

Rust  of  Cheoris  {Puccinia  chloridis  Diet.). 

The  uredoform  of  this  rust  is  sometimes  very  abundant  on  Chloris 
verticillata  in  the  Great  Plains  region,  occurring  in  late  summer  and 
autumn.  The  sori  are  deep  brown  in  color.  The  uredospores  germi- 
nate very  freely  and  easily.  In  a  number  of  experiments  made  in 
1898  it  was  found  that  the  uredo  on  C.  verticillata  and  ( '.  elegans 
would  readily  transfer  from  either  host  to  the  other,  but  not  to  other 
grasses,  in  several  cases  which  were  attempted.  In  a  wat«h-glass  cul- 
ture, made  March  L8,  L898,  of  uredospores  from  C.  elegans,  produced 
from  artificial  infection  in  a  greenhouse,  not  only  these  spores  germi- 
nated freely,  but  a  number  of  newly  formed  teleutospores  al  the  same 
time,  an  occurrence  unusual  except  in  the  Lepto-uredinese.  Among 
thousands  of  cultures  made  by  the  writer  only  one  other  instance  of 
this  kind  has  occurred.  In  the  summer  of  L895  at  the  Biological  Lab- 
oratory at  Cold  Spring  Harbor.  Long  Island,  both  teleutospores  and 
uredospores  taken  from  the  same  sorus  id'  a  rust  on  Luzula  campestris 
gave  good  germinations.6 

Rusts  of  Willow  and  Cottonwood  (Melampsora). 

Both  the  uredospores  and  teleutospores  of  the  rusts  of  willow  and 
cottonwood  germinate  readily,  the  germ  tubes  of  the  latter  containing 
always  brilliant  endochrome.  Healthy  leaves  of  either  cottonwood  or 
willow    placed   in   a   damp  chamber   have  often   been    infected    by   the 

a  Arthur  describes  culture  experiments  made  by  his  assistant,  William  Stuart,  in 
.Inly,  L898,  in  which  wheat  plants  were  infected  with  uredospores  from  this  host, 
hut  the  spores  of  the  infection  sori  were  larger  than  these  of  the  original  material. 
(Bui.  Lab.  Nat.  Hist,  state  Univ.  Iowa,  vol.  I.  No.  1,  pp.  396  397,  1898.) 
liic  species  was,  without  much  doubt.  Puccinia  obscura  Schroet. 


WINTER    RESISTANCE     OF    THE    UREDO.  L9 

wrih'i  in  nine  to  twelve  days.  The  incubation  period  is  tnuch  short- 
ened by  using  germinating  spores  in  the  inoculations.  In  the  month 
of  October,  at  Manhattan,  Kans.,  an  infection  was  produced  in  tin- 
way  in  three  da^  s. 

It  was  attempted  by  numerous  inoculations  with  the  uredoform, 
chieih  at  Washington,  I>.  ('..  to  transfer  the  rust  from  willow  to  cot- 
tonwood  and  the  reverse,  bul  always  without  success.  An  interesting 
feature  of  thesa  experiments  was  the  discovery  of  the  fad  that  the 
cottonwood  mosl  common  in  Washington,  known  as  South  Carolina 
poplar,  could  not  be  infected  by  the  uredoform  from  the  common 
Western  cottonwood,  though  these  two  poplars  are  classed  h\  some  as 
being  the  same  species.  Moreover,  the  rust  does  not  occur  in  nature 
on  the  South  Carolina  poplar,  bul  is  very  abundant  on  the  Western 
cottonwood,  and  even  occurs  in  Washington  on  the  tew  individual 
trees  of  that  type  growing  in  the  city. 

WINTER  RESISTANCE  OF  THE  UREDO. 

In  another  bulletin"  the  writer  has  given  in  detail  the  observations 
ami  culture  experiments  proving  the  successful  wintering  of  the  uredo 
in  the  orange  leaf  rust  of  both  wheat  and  rye.  In  this  connection  it 
i-  eu-\  t.i  3ee  a  number  of  closely  correlated  facts,  which  may  mutually 
explain  each  other:  (1)  As  shown  under  the  preceding  topic,  the  uredo 
of  black  stem  rust  may  infect  a  number  of  different  hosts,  ami  there- 
fore ha>  a  manifoldly  greater  chance  of  propagation  with  the  same 
mun her  of  uredospores  than  if  there  were  hut  one  possible  host;  (2)  as 
also  shown,  the  uredo  of  orange  leaf  rust  is  restricted  in  every  case  to 
hut  one  host,  or  at  mosl  to  hut  one  genus,  and  a  much  greater  produc- 
tion of  uredospores  is  therefore  necessary  for  the  life  of  the  species 
in  this  stage;  (3)  as  a  corresponding  matter  of  fact  it  is  well  known 
that  the  uredo  of  the  latter  rust  exists  usually  in  very  much  larger 
quantity  than  that  of  the  former;  i  1 1  on  the  other  hand,  the  teleuto 
sporic  stage  is  the  prevailing  form  of  the  stem  rust,  which  fact  makes 
this  rust  usually  the  more  damaging  of  the  two.  a- the  teleutospores 
infest  the  stem  chiefly,  thus  more  directly  interfering  in  plant  nutri 
tion;  (5)  the  stem  rusl  is  proved  to  he  connected  with  the  barberry 
rust,  thus  giving  it  an  additional  chance  for  increased  propagation, 
ami  this  through  tic  medium  of  the  teleuto  stage  instead  of  the  uredo; 
(6)  finally,  the  uredo  being  the  prevailing  form  of  the  leaf  rust,  and 
Dosecidial  form  being  known  in  this  count  ry,''  it  would  seem  necessaiy 
that  this  stage  of  that  rusl  should  be  very  hardy  in  order  to  endure 
extremes  of  cold  and  drought  and  preserve  the  life  of  the  species. 
Previous  investigations  of  the  writer  and  others  have  amplj  proved 
that  tin-  is  the  case.     In  t  he  meantime  it  is  found  that  in  other  species 


"Cenal   Rusts  -i  the  United  State-.  Bul.  16,   Div.  Veg.    Phya.  and   Path.,    I' 
Dept.  of  Agriculture,  pp.  21  -l'::.  ami  II,  !■">. 

cept  in  the  case  of  the  form  on  /   ijmua  virgin         i  ready  mentioned, 


20 


INVESTIGATIONS    OF    RUSTS. 


there  exists  a  similar  hardiness  of  the   uredo,  of   which  cases  the  fol- 
lowing will  be  discussed  here: 

Uredo   of  Kentucky  Bluegrass  Rust  (Puccinia  poarum  Niels.). 

The  writer  has  known  for  some  time  that  the  uredo  stage  of  the  blue- 
grass  rust  is  able  to  pass  the  winter  alive  and  in  germinating  condition 
during  any  season  as  far  north  as  Lincoln,  Nebr.,  but  additional  evi- 
dence has  been  obtained  from  time  to  time.  At  the  same  time  it  is  sig- 
nificant that  there  is  no  record  that  the  teleutospores  have  ever  been 
found,  except  in  one  instance,  at  the  above-named  place.  In  fact,  lew. 
if  any,  uredot'orms  so  hardy  as  this  one  exist  in  this  country.  On 
February  1,  1893,  this  uredo  was  still  alive  in  the  vicinity  of  .Man- 
hat  tan.  Kans.  Every  month  of  the  year  it  exists  alive  and  growing  in 
great  abundance  everywhere  about  Washington,  D.  C.  On  March  2, 
1898,  it  was  found  fresh  on  green  leaves  of  the  host  at  Lincoln.  Nebr. 
On  the  same  spot  of  ground  it  was  still  growing  and  spreading  rapidly 
on  May  8  of  the  same  year.  Host  plants  were  transplanted  that  day 
into  a  greenhouse,  where  the  rust  continued  to  increase  rapidly.  As 
would  now  be  supposed,  the  rust  is  sharply  limited  to  its  one  host. 
Kentucky  bluegrass.  The  results  of  the  following  cultures  may  be 
given  in  evidence. 

Table  IN" . —  Cullun  experiments  with  the  uredo  of  Kentucky  bluegrass. 


Date. 

Locality. 

Origin  of  inoculat- 
ing material. 

Plant  inoculated. 

Period 
of  incu- 
bation 
in  days. 

Result. 

Manhattan,  Kans  . 
do 

Poa  p  att  nsis 

w  heat 

18 

is 
16 

11 

11 
13 

13 

is 

10 

Ho 

Oats 

Do 

Dec.  21,  L89i 
Jan.  22  1897 

Washington,  D.C.. 
do 

Rye    {Uredo  rubigo- 
V/hed   ( '  redo    jra- 

minis). 
.Id 

..    do. 

Do 
Do 

Do... 

noralis 

Poa  pratensls 

Do. 

1 897 . . . 

..  do 

Rye   ( ( Vi  do  rubigo- 
do 

Do 

Do . . . 

do 

Do. 

Feb.  13, 1897.. . 

...do 

Wheal  <  1       ' 

vera). 

itensis 

...  .do 

Do. 

Feb    15, 1 B97 

.do.  . 

Uredo  of  Puccinia  montanensis  Ell. 

This  is,  in  some  respects,  one  of  the  most  interesting  of  grass  rusts. 
It  is  one  of  the  "covered  rusts,"  and  is,  indeed,  so  far  covered  that  it 
is  often  entirely  overlooked  by  collectors.  The  uredosori  are  very 
Uniform  in  size  and  are  exceedingly  small,  it  being  necessary  often  to 
examine  them,  or  even  find  them,  with  a  hand  lens.  They  are  ellip- 
tical in  shape  and  placed  end  to  end  in  long,  narrow,  yellow  striae 
between  the  veins  of  the  leaf.  The  teleuto  stage  is  so  far  hidden  as 
to  be  detected  only  by  a  faintly  darker  color  beneath  the  leaf  epi- 
dermis.    The   rust   is   the   most    nearly  like    /'.  glvmarum   Eriks.  and 


EMERGENCY    ADAPTATIONS.  lM 

Ilciin.  ye\  found  in  this  country.  The  known  hosts  are  Elymus  cana- 
densis &nd  /:.  virginicas,  but  it  seeuis  to  occur  on  other  hosts.  Whether 
the  forms  on  different  hosts  can  be  transferred  from  one  to  another 
is  not  \  et  fully  determined: 

The  important  fact  now  known,  however,  is  thai  the  nredoform  is 
able  tt>  preserve  the  species  over  the  winter  without  the  intervention 
of  other  stages,  though  it  is  possible  that  extensive  propagation  is 
aided  by  other  stages.  October  28,  1897,  fresh  uredosori  were  observed 
on  Elymus  canadensis  at  Manhattan,  Kans. ,  and  again  in  the  same 
locality  on  November  2.  But  as  early  in  the  spring  as  May  26,  at 
Lincoln  Nebr.,  when  there  was  yet  but  a  small  beginning  of  vegetation, 
the  uredo  had  burst  the  epidermis  of  the  host  in  grass  plats  at  the 
University  farm.  Previous  to  this  the  living  uredo  had  been  observed 
in  the--e  plats  practically  even  month  of  the  winter. 

[n  other  instances  the  uredospores  of  certain  species  are  so  very 
abundant  and  the  teleutospores  so  rare  that  there  seems  a  probability 
that  such  species  are  carried  over  from  summer  to  summer  largely 
through  the  uredo  stage  alone,  though  there  is  no  absolute  proof  of 
such  a  cour>e.  Two  instances  are  particularly  interesting  those  of 
the  uredos  of  Puccinia  cryptandri  Ell.  and  Barth.,  and  Puccini  a  on 
Panicuni  autumnale.0  The  uredospores  of  these  species  begin  to  be 
conspicuously  abundant  about  midsummer,  but  continue  in  consider- 
able abundance  until  very  late  in  autumn.  The  uredo  of  Panicuni 
autumnal i  was  found  in  germinating  condition  in  Kansas  up  to  Novem- 
ber 3  in  L897.  A  water-drop  culture  of  uredospores  of  this  species 
gave  excellent  germination  in  ten  hours  August  21,  1897,  at  Perkins, 
Okla.  The  uredospores  of  Pucciniacryptandri  were  found  in  extreme 
abundance  in  Oklahoma  until  October  11,  1897,  but  in  all  cases  with- 
out any  accompanying  teleutospores.  Often  the  uredosori  had  a  fresh 
appearance  on  portions  of  leaves  that  were  quite  dead. 

EMERGENCY  ADAPTATIONS. 

In  connection  with  some  culture  experiments  conducted  at  Lincoln, 
Nebr.,  in  the  botanical  laboratory  of  the  State  University,  in  February, 
lv'.'^.  a  water-drop  culture  was  made  (February  3)  of  uredospores  of 
the  above-mentioned  Puccinia  cryptandvi  which  had  been  collected  on 
October  8,  1897,  at  Perkins.  Okla..  and  kept  to  date  as  herbarium 
specimens.  A  fair  germination  resulted  in  twentj  four  hours.  Spores 
from  the  same  collection  were  used  on  February  16  to  inoculate  seed 
lings  of  Y"'"1'""' "s  airoides,b  with  the  result  of  the  appearance  of  two 
rust  spots  bj  March  16.  These  spots  ma\  really  have  appeared  much 
earlier  and   been  overlooked,  as  they  were  very  small   and  the  host 


Pi  rhaps  a  new  species,  n Jiiilt  further  study. 

^Apparently  this  same  Bpecies  of  rust   had  already  been  collected  <<t\  Sporoliolus 
in  the  same  locality  where  the  collection  fr S.  •  ry/ilandri  was  made. 


22  INVESTIGATIONS    OF   RUSTS. 

itself  is  well  known  to  have  extremely  narrow  leaves.  Moreover,  the 
8  pores  were  not  germinated  when  applied,  and,  bring  from  dried  speci- 
mens, the  incubation  period  would  naturally  be  long.  Seedlings  of 
/S.  cryptandri  were  not  at  the  time  available.  On  March  16  a  second 
water-drop  culture  was  made  from  this  dried  material,  resulting  in  the 
germination  of  a  few  spores. 

Teleutospores  from  herbarium  specimens  have  often  been  germi- 
nated, but  the  writer  knows  of  no  other  instance  of  the  germination 
of  dried  uredospores,  such  spores  being  able  also  to  infect  a  different 
host.  These  observations  and  experiments  indicate  that  we  have 
here  a  second  step  in  the  perfection  of  the  uredo  stage  as  a  means  of 
propagating  the  species.  The  tirst  step,  the  attainment  of  sufficien 
hardiness  to  continue  alive  in  the  green  plant  over  winter,  has  just 
been  discussed.  Even  in  this  case  the  uredo,  although  quite  active. 
at  least  displaces  the  resting  spore,  and  in  a  measure  performs  its  pari . 
But  as  the  perennial  host  becomes  more  like  an  annual  and  the  plant 
dies  nearly  or  quite  to  the  ground,  as  in  this  particular  case  of  the 
Sporobolus  (which  is  quite  different  in  this  respect  from  the  evergreen 
Poa pratensis,  for  example),  necessarily,  in  the  absence  of  teleuto- 
spores, the  uredospore  must  be  able  to  infect  after  a  dormant  period. 
The  uredospore  therefore  becomes  now  practically  a  resting  spore, 
but  retains  the  appearance  and  manner  of  germination  of  the  summer 
spore.  Such  a  modification  in  form  or  function  of  any  stage  of  a 
species  to  correspond  with  an  unusual  change  of  condition  of  climate 
or  of  the  host  may  be  considered  as  an  emergency  adaptation. 

It  is  easily  understood  how  the  change  of  conditions  may  be  so 
severe  as  to  necessitate  still  further  modification  of  structure  as  well 
as  function,  simply  as  a  means  of  protection.  Such  a  development 
seems  to  have  been  actually  reached  in  the  species  next  discussed, 
which  has  resulted  in  the  production  of  a  distinct  spore  form,  special- 
ized from  the  uredo.  leaving  still,  however,  a  true  uredo  stage  for 
summer  propagation. 

PUCOINIA    VEXANS    FAKL. 

There  are  probably  no  other  species  in  all  the  Uredinese  more  inter- 
esting than  this  one,  and  certainly  none  that  has  been  more  perplex- 
ing. In  this  species  there  are  three  distinct  spore  f  on  us  aside  from  any 
secidium  or  spermogonium  that  may  possibly  exist  true  uredo  and 
teleuto  stages,  and  a  peculiar  one-celled  form  different  from  either  of 
these.  (PI.  II,  tigs.  2  !».)  The  species  was  at  fust  made  all  the  more 
puzzling  by  the  rarity  of  the  true  uredo  stage,  which  was  not  known 
to  exist,  or  at  least  not  reported,  until  L890,  when  Dr.  II.  J.  Webber, 
in  the  Catalogue  of  the  Flora  of  Nebraska,  reported  its  occurrence  in 
that  Stale.  In  certain  seasons  ami  localities  I  he  teleuto  stage  also  is 
almost  or  entirely  lacking1. 


PTTCCIN1  \    VEX  \N-    FARL.  23 

The  species  was  first  described  h\  Peck  as  a  Uromyces(?Z  Irmndegei 
l'k.i  .in  the  basis  of  material  collected  by  Mr.  T.  >.  Brandege,  in 
which  specimens  contained  only  the  third  spore  Porm.  Because  of  the 
discovery  afterwards  of  two-celled  spores  associated  with  this  third 
spore  form,  even  sometimes  in  the  same  sorus,  Doctor  Farlow  described 
it  as  a  Puccinia  </'.  vexans  Farl.)  in  the  Proceedings  of  the  American 
Academy  of  Arts  and  Sciences,  Vol.  XVIII,  pp.  S2  S3.  At  that  time 
the  true  uredo  stage  bad  not  been  discovered. 

This  third  spore  form  is  far  more  prevalent  than  either  of  the  others 
as  a  rule,  bul  is  sometimes  entirelj  absent,  leaving  only  the  teleuto 
stage.  It  is  distinct  from  either  of  the  other  forms  in  structure  and 
appearance,  and  yet  resembles  both  in  some  respects.  It  is  larger  than 
either  of  them,  i-  strongly  papillate,  and  ha-  a  much  thicker  cell  wall. 
but  on  the  other  hand  possesses  the  color  and  persistence  of  pedicels 
of  teleutospores  ami  appears  to  have  pores  like  the  uredospores.  (PI. 
II.  fig.  5. )     Doctor  Farlow,  in  his  description,  says: 

\  species  in  which  some  of  the  sori  contain  only  two-celled  spores  must  certainly 
!  i..  be  a  Puccinia,  and  the  perplexing  question  arises,  are  the  one-celled  spores 
a  unilocular  form  of  teleutospores  similar  to  what  is  known  in  /'.  cesatii  Schr.,  or  are 
ilny  the  uredospores  of  this  species?  1  have  not  heen  able  to  find  any  other  spores 
which  represent  the  uredo  of  the  species;  ami  never  having  seen  the  unicellular 
spores  in  germination,  there  i>,  -•>  far  as  we  yet  know,  no  reason  why  they  may  not 
be  the  uredospores.  On  the  other  hand,  their  general  appearam  e  ami  the  density 
of  the  cell  wall  would  lead  one  to  suppose  that  they  were  of  a  teleutosporic  nature. 
Further  conjecture  is  unnecessary,  because,  as  the  species  is  not  at  all  rare  in  some 
localities,  botanists  who  can  examine  the  fungus  on  the  spot  ought  to  he  able  t<> 
ascertain  whether  the  one-celled  I""  lies  produce  promycelia  or  not,  or  else  to  discover 
the  line  uredo  of  the  species. 

A  full  description  of  all  three  forms  is  given  by  Arthur  ami  Holway 
in  Descriptions  of  American  Uredineaa  accompanying  Fasiclo  [V  of 
I  redinese  Exsiccatae  el  [cones. 

After  numerous  unsuccessful  trials  during  several  years,  the  writer 
was  finally  able  to  germinate  the  third  spore  form.  and.  as  suggested 
by  Doctor  Farlow,  has  in  this  way  heen  able  to  determine  its  nature. 
In  manner  of  germination  it  is  exactly  like  the  uredospore,  the  long 
simple  germ  tubes  being  produced  through  equatorial  pores  (PI.  II, 
figs  7  and  8),  but  is  like  the  teleutospore  in  germinating  only  after  a 
dormant  period  and  exposure  to  extremes  of  weather.  The  uredo  ami 
teleuto  forms  being  already  presenl  and  morphologically  differenl 
from  this  form,  ii  musl  he  considered  distinct.  Because  of  the  dual 
nature  of  this  spore  form,  the  writer  has  already  proposed  for  it  tin' 
name  amj)/tisport  in  a  paper  read  before  the  Baltimore  meeting  of  the 

Societ}' for  Plant  Morphology  and  Physiology  in  1- ,  onl\  an  ihstrad 

of  which  was  published.        The  term  has  since  heen  adopted  by  Arthur 

I'-'    I  ..i/.,  -J:   r_>7. 

Bul.  Lab.  Nat.  Hist.  Man-  Univ.  Iowa,  Vol.  Y,  pp.  :;■_".<  330. 

-nee.    Vol.    XIII,   p.  250. 


24  INVESTIGATIONS    OF    RUSTS. 

and  Holway,"  and  a  second  instance  of  the  occurrence  of  this  form  is 
described  by  them  for  Puccinia  tripsaci  Diet,  and  Holw.  The  entire 
series  of  observations  and  experiments  with  this  species  made  by  the 

write]-  will  now  be  described. 

The  first  cultures  of  amphispores  were  made  January  L5,  L894,  at 
Manhattan,  Kans.  Both  a  water  culture  and  one  of  a  sterilized  decoc- 
tion of  manure  were  employed,  with  no  result,  the  chief  cause  of  fail- 
ure being  probably  that  the  experiment  was  too  early  in  the  season. 
Afterwards  numerous  other  trials  were  made  with  no  better  success. 
In  the  meantime  true  uredospores  were  found  on  September  25,  L896, 
at  Manhattan.  Kan-. 

Finally  a  successful  culture  of  the  amphispores  was  made  on  March 
8,  1897,  at  Washington,  D.  C.  The  germination  was  excellent.  An 
abundance  of  rather  lone-  germ  tubes,  not  promycelia,  was  produced 
in  forty-two  hours,  but  only  one  to  each  spore.  These  germ  tubes, 
unlike  those  of  most  uredospores.  are  quite  colorless  and  clear.  A  few 
teleutospores  were  present,  none  of  which  germinated.  The  culture 
was  an  ordinary  water  drop,  but  was  made  in  a  new  form  of  culture 
cell,  constructed  to  special  order  and  similar  to  the  Van  Tieghem 
cell,  except  that  the  elass  ring  is  quite  thin  and  drawn  out  into  an 
open  tube  on  each  of  two  opposite  sides,  with  the  opening  plugged 
with  cotton  wool,  thus  admitting  sterilized  air.  This  construction  may 
or  may  not  have  increased  the  chances  for  germination.  The  extreme 
weather  conditions  at  the  time,  to  which  the  specimen-  were  first 
exposed,  probably  contributed  most  to  the  success  of  the  culture. 
They  were  fastened  to  the  roof  of  a  near-by  shed,  and  after  several 
days  of  warm  sunshine  were  thoroughly  soaked  with  rain,  which  was 
followed  by  snow  and  then  a  severe  freeze,  soon  after  which  the  cul- 
ture was  made.  It  is  an  interesting  feature  of  the  experiment  that 
the  specimens  were  received  from  Dr.  David  Griffiths,  then  at  Aber- 
deen, S.  Dak.,  and  had  been  collected  in  September,  1896,  and  kepi  in 
the  herbarium  until  sent  to  Washington.  It  was  unfortunate  that 
seedlings  of  the  host  were  not  available  for  making  inoculations  with 
these  perfectly  viable  spores.     Such  an  experiment  is  yet  to  be  made. 

At  .Manhattan.  Kans..  in  1897,  the  uredo  was  present  in  considerable 
abundance  from  June  until  late  in  October  in  grass  plats  on  the 
Experiment  Station  farm.  On  duly  S  inoculations  were  made  with 
the  uredospores  of  this  species  and  with  iridium  cephalanthi  and 
. /■'.  xanthoxyli  on  seedlings  of  Bouteloua  racemosa  without  result. 
Further  inoculations  with  uredospores  on  October  4  were  successful, 
rust  spots  appearing  in  twelve  days  (Fl.  II.  lie.  '■').  followed  in  nine 
more  davs  with  one  sorus  of  amphispores.  The  uredosori  are  yel- 
lowish-brown and  rather  inconspicuous.  On  December  31  uredo- 
spores could  not  be  found  in  the  grass  plats  at  Manhattan. 

"Bui.  Lab.  Nat.  Hist.,  State  Univ.  towa,  Vol.  V,  p.  I7.'>. 


RXPERIMEN  rS    WITH     I.I  PTO-1   111-  KIM    1  . 

At  Lincoln,  Nebr.,  a  water-drop  culture  was  made  of  Puccinia 
vexa/is'on  March  L5,  LS98,  resulting  in  a  few  germinations  of  the  teleu- 
tospores  in  three  days.  Long  pronrycelia  were  produced,  bul  no 
sporidiola.     Nunc  of  the  numerous  amphispores  present  germinated. 

On  September  29,  L899,  all  three  spore  forms  were  again  found  in 
the  grass  plats  at  Manhattan.  Living  hosl  plants  were  transferred  i<> 
Washington,  1>.  C,  and  seedlings  were  started  for  further  experi- 
ments, when  other  duties  intervened  and  the  work  could  not  be 
continued. 

Certain  facts  concerning  the  relative  abundance  of  the  amphispores 
and  teleutospores  in  differenl  seasons  and  localities  seem  to  harmonize 
quite  well  with  the  idea  already  expressed  as  to  the  function  of  the 
former.  If  it  is  the  work  of  the  amphispore  to  carry  the  species 
through  unusually  severe  cold  or  drought,  then  this  spore  form  should 
lie  relatively  more  abundant  in  dr\  periods  and  relatively  more  com- 
mon to  the  westward  and  northward  in  the  Great  Plain-.  These  con 
ditions  are  jusl  whal  exist.  The  amphispore  prevails  almost  entirely 
in  the  Dakotas  and  in  western  Kansas,  western  Nebraska,  and  eastern 
Colorado,  and  appears  to  have  been  more  common  in  eastern  Kansas 
during  a  dry  period  of  several  years  than  during  a  wet  period.  At 
the  same  time  westward  toward  the  mountains  there  i-  less  chance  for 
an  .Kcidiuni  to  connect  with  the  teleuto  -lane. 

EXPERIMENTS    WITH    LEPTO-UREDINEJE. 

It  is  generally  supposed  that  teleutospores  which  ahx  followed  by 
an  tecidium  germinate  only  after  a  considerable  period  of  rest,  usually 
in  early  spring.  As  already  mentioned  under  the  discussion  of  sun- 
flower rust,  the  writer  germinated  teleuto- pore-  of  this  species  readily 
in  the  autumn,  and  afterwards  at  differenl  times  during  the  winter. 
This  readiness  of  germination,  apparently  at  almost  au\  dale,  is  an 
indication  in  itself  of  an  alliance  to  the  lepto  species.  But,  more  than 
this,  the  autumn  inoculation- with  material  in  which  no  uredospores 
could  positively  be  detected  nevertheless  were,  in  some  cases  at  least, 
followed  first  by  spermogonia  and  then  bj  the  uredo!  <  )f  course  occa- 
sional uredospores  that  may  have  been  overlooked  could  have  produced 
those  few  spots  in  which  the  presence  of  spermogonia  was  not  certain. 
Here,  then,  i-  further  evidence  of  the  lepto  tendency  of  the  species. 
In  addition,  it  i-  well  known  that  the  a?cidium  i-  rare  and  appeal's  to 
have  no  fixed  time  of  occurrence.  Now.  onl\  the  omission  of  the 
uredo  is  needed  to  make  the  rust  a  real  lepto  species.  A-  it  i-.  it- 
position  ;-  more  nearly  that  of  a  Hemi  puccinia  than  of  an  autcecious 
species.  Experiments  of  this  kind,  united  with  critical  field  observa- 
tions, thus  throw  much  light  upon  classification  a-  to  group  position, 
a-  well  a-  enabling  us  to  connect  stages. 

<  )u  the  other  hand,  certain   lepto  species  will  he  found  to  closely 


26  INVESTIGATIONS    OF    RUSTS. 

approach  other  groups,  and,  indeed,  after  further  experiment,  may 
have  to  be  placed  in  some  other  group.  The  following  species  have 
given  interesting  results  in  culture  experiments. 

Rust  of  Cocklebur  (Puccinia  xanthii  Schw.). 

Observations  and  culture  experiments  of  the  writer  show  that  the 
rusl  of  cocklebur  is  probably  limited  to  one  host  and  is  distinct  from 
the  species  on  Ambrosia,  and  also  justify  the  suspicion  that  it  lies  very 
near  the  border  of  the  Lepto-uredinese,  and  may  belong  to  another 
group. 

On  March  1,  1897,  the  first  water-drop  culture  made  gave  an  excel- 
lent germination  in  forty-eight  hours.  Long  promycelia  were  pro- 
duced, but  no  sporidiola.  On  February  13,  L897,  at  Washington. 
D.  C,  inoculations  were  made  on  seedlings  of  cocklebur  and  Ambrosia 
trifida,  resulting  in  an  infection  of  the  former  in  eighteen  days,  but 
not  of  the  latter.  On  March  12  a  second  experiment  resulted  in  a 
large  number  of  infections  of  cocklebur  seedlings  in  fourteen  days. 
In  all  these  cases  spermogonia  preceded  the  teleutospores  in  the 
infected  spots.  On  October  8  of  the  samej^ear  an  aecidium  was  found 
on  cocklebur  in  considerable  abundance,  associated  with  the  teleuto- 
sori.  at  Perkins,  Okla.  An  inoculation  on  cocklebur  seedlings,  made 
at  Lincoln,  Nebr.,  on  February  l(i.  L898,  resulted  in  the  production 
of  spermogonia  in  ten  days.  The  inoculating  material  had  been  col 
lected  in  October,  L897.  An  aecidium  on  cocklebur  was  again  found 
in  abundance  at  Las  Cruces,  N.  Mex.,  on  duly  II.  L899.  Attempts 
should  be  made  to  infect  the  cocklebur  with  this  secidium.  Doctor 
Farlow  says  an  secidium  on  Xanthium  in  Massachusetts  is  frequently 
followed  by  Puccinia  xanthii.0. 

The  ease  with  which  artificial  infections  are  made  with  this  rusl  is 
at  first  sui-prising.  So  long  as  there  i-<  warmth  and  moisture,  germina- 
tion occius  under  almost  any  condition  and  at  any  time. 

Rust  of  Velvet  Leaf  (Puccinia  heterospora  B.  and  ('.). 

In   the  last-mentioned  experiments   the   inoculating   material  was 

taken  each  time  from  dead  leaves.  The  same  was  true  in  one  experi- 
ment with  the  rust  of  velvet  leaf.  November  1-1.  L896,  at  Manhattan, 
Kans..  in  which  seedlings  of  the  host  were  infected  in  twelve  days. 
For  all  these  experiments  the  average  time  of  incubation  was  about 
twelve  days.  In  December,  L896,  the  infected  plants  of  the  last 
experiment  were  transferred  from  .Manhattan  to  Washington.  D.  C, 
and  material  From  these  was  used  to  inoculate  new  seedlings,  which 
resulted   in  an  infection  in  nine  days.      It   appears,  therefore,  that  the 

"Proc.  Amer.  Acad.  Arts  and  Sci.,  Vol.  Will,  p.  75. 


PERENNJ  \l.    SPECIES.  '11 

incubation  period  is  shorter  if  inoculating  material  is  taken  from  liv 
ing  plants,  and  during  the  summer  il   is  probably  about   the  same  as 
that  of  infections  from  uredospores. 

Numerous  experiments  were  also  made  with  other  lepto  specie-. 
including  Pucchria  grindelix,  l'k..  /'.  variolans,  Hark..  /'.  lygodesmix, 
Y..  and  E.,  and  /'.  sherardlaitti,  K6rn,  with  results  similar  to  those 
above  mentioned.  The  writer  1  in -.  already  called  attention  to  ihe 
phenomenon  of  the  formation  of  ratenulate  sporidiola  in  two  of  these 
species,  /'.  gi'liidelin  and  /'.  variolanx." 

PERENNIAL    SPECIES. 

The  chance  for  the  continued  existence  of  a  rusl  through  winter 
resistance  of  the  uredo  without  the  intervention  of  another  stage  has 
been  discussed.  Though  such  a  condition  can  only  exist  on  a  peren- 
nial host,  or  at  least  one  thai  lives  over  winter,  it  must  not  be  sup- 
posed that  the  fungus  itself  is  necessarily  or  even  usually  perennial. 
As  fa-t  as  the  leaves  of  the  host  die  the  spores  simply  drop  on  to  the 
next  lower  and  younger  leave-  and  produce  reinfection,  the  mycelium 
not  extending  through  the  base  of  the  infected  leaf  into  the  next 
leaves.  If.  however,  the  mycelium  is  found  within  the  rootstock  and 
after  a  dormant  period  during  midwinter  follows  the  new  -hoots 
upward  in  early  spring  and  again  produces  sori  at  the  surface  of  the 
plant,  the  rust  is  a  true  perennial.  This  condition  appeal-  to  exist  in 
the  follow  ing  species. 

.Ki  Hill  VI     ll   BERCULATUM     E.    AM)    K. 

It  i-  now  u-uallv  supposed  that  all  aeidial  forms  will  likelv  lie  found 
to  lie  connected  with  other  stages,  though  there  aie  probably  more  of 
these  form-  whose  connection-  are  at  present  undetermined  than  there 
are  of  Lepto-uredinere.  If  any  .Kcidimn  is  more  likely  than  another 
to  lie  an  independent  species,  certainlv  the  probabilities  are  largely  in 
favor  of  this  species, which  occurs  on  Callirrhot  invohtcrat<t,b  for  there 
i-  no  need  of  another  stage  to  perpetuate  it.  though  another  host 
might  u'iv  e  il  a  w  ider  dist  ribution. 

The  striking  orange  yellow  color,  large  and  otherwise  conspicuous 
sori,  and  it-  complete  attack  of  everj  portion  of  the  host  make  this  an 
unusually  unique  and  attractive  species  (PI.  I.  frontispiece).  A  note  con- 
cerning the  hardiness  of  this  species  was  published  l>v  the  writer  sev- 
eral years  ago.      The  word- are  here  quoted:  "jEcidivm  tuhercidatum 

"  Bot,  Gaz.,  Vol.  Will.  pp.  155   156 

'* Tin >iil_'Ii  ii. ii  previously  reported,  this  rust  we  founil  also  on  ('aUirrhot   <th 
:\\  Salina,  Kans.,  in  May,  1893. 
■  Bot.  Gaz.,  Vol.  Will.  p.  I.',::. 


28  INVESTIGATIONS    Oh{    BUSTS. 

E.  and  K.is  still  producing  secidiospores  on  ( 'aUirrhot  invohicrata  out- 
doors here  tit  Manhattan  al  the  time  of  this  writing  (October  L5,  L893), 
and  Mr.  E.  Bartholomew,  of  Rooks  County,  Kans. ,  tells  rne  that  be  lias 
seen  in  December  aecidiospores  on  specimens  of  this  host  growing  close 
by  a  large  snowdrift.  In  the  spring  aecidiospores  of  this  species  begin 
forming  about  the  first  day  of  April."  On  December  20,  1893,  after 
the  above  was  transmitted  for  publication,  the  rust  was  found  still  alive 
although  it  had  boon  under  4  inches  of  snow.  In  a  water-drop  cul- 
ture of  some  of  the  material  four  spores  germinated  in  twenty-four 
hours.  Since  that  time,  at  later  dates  in  the  winter  the  living  rust  has 
been  found,  but  close  within  the  rootstock,  with  a  faint  color  still, 
but  producing  no  spores.  The  peculiar  manner  of  growth  of  the  rust, 
permeating  the  entire  host  and  producing  scattering  sori  all  along 
the  stems  to  their  liases,  as  well  as  on  the  leaves,  and  the  difficulty  of 
germinating  the  spores  harmonize  also  with  the  idea  of  a  propagation 
by  perennial  mycelium.  Besides  the  above  instance  other  cultures  of 
the  spores  were  made  as  follows:  At  Manhattan.  Kans.,  May  •_'<».  L893, 
spores  from  Callii'rhot  alexoides,  only  a  few  germinations  in  forty- 
eight  hours;  at  Manhattan,  June  '.».  L893,  spores  from  ('.  involucrata 
germinated  sparingly  in  twenty-five  hours;  at  Manhattan.  January  30, 
1894,  spores  from  ('.  involucrata  growing  in  greenhouse,  fair  germi-  < 
nation  in  sixty  hours. 

In  the  winter  of  L896-97  infected  plants  of  ('.  involucrata  wore 
obtained  from  Kansas  and  grown  in  a  greenhouse  at  Washington, 
D.  C,  and  on  March  IT.  L897,  inoculations  of  seedlings  of  the  follow- 
ing grasses  with  spores  from  those  plants  failed  to  produce  infections: 
Agropyron  occidentale,  A.  richardsoni,  Sitanion  elymoides,  Elymus 
canadensis,  and  Bovteloua  racemosa. 

Rust  of  Peucedanum  Fceniculaceum. 

An  ^Ecidium  occurs  on  this  host  in  Kansas  and  Nebraska  which  lias 
been  reported  as  jE.  anisotomes  Reich.,  but  the  identity  of  which  is 
not  yet  determined"  satisfactorily  to  the  writer.  At  certain  places  a 
Puccinia  follows  the  .Ecidium  so  closely  that  their  connection  is  very 
probable.  Both  forms  are  particularly  abundant  at  Manhattan.  Kans. 
On  April  25,  L893,  at  that  place,  it  was  determined  by  the  study  of 
many  cross  sections  of  the  host  plant  that  the  mycelium  of  the  iEcid- 
ium  extends  into  the  rootstock.  Lt  is  one  of  the  earliesl  rusts  in  the 
spring  to  appear  in  that  locality.  These  facts  make  it  probable  that 
this  rust  is  also  perennial.  On  the  other  hand,  it  is  possible  that  the 
teleutospores  of  the  Puccinia  ma\  produce  a  very  early  infection  at 
the  base  of  the  young  shoots,  resulting  in  the  .Kcidium.  although  in 
some  localities  no  Puccinia  has  yet  been  found  following  the iEcidium. 

«The  species  is  probably  Puccinia  jorn  sii  I'k.,  with  the  tecidial  stage  present. 


i:i  3T    OF    PEUCEDANUM     bXENICl   LA<  El   M.  29 

At  Lincoln,  Nebr.,  on  March  l'I.  1898,  teleutospores  of  this  same  Puc- 
cinia  germinated  in  a  water  drop  culture  in  twent}   four  hours. 

It  should  be  noted  thai  it  is  possible  for  a  perennial  rust  to  exist  in 
an  annual  li<>-t .  the  in\  tvlium  of  the  rust  being  carried  over  winter  in 
the  seed  of  the  host.  Such  an  instance  is  practically  certain  in  the 
Euphorbia  rust  already  discussed.  Granting  thai  Doctor  Eriksson's 
experiments  were  accurate,  there  would  be  another  example  in  Puc- 
ciniu  glumarum  Eriks.  and  rlenn.  on  svheat. 


PLATES. 


;;i 


DESCRIPTION  OF  PLATES. 

Plate  I.  Frontispiece.  A  perennial  rust.  /Ecidium  tuberculatum  E.  and  K.  on  Cal- 
lirrhoe  involucrata  <  Jr. 

Plate  II.  Fig.  L.  — Seedling  of  Euphorbia  dentata  grown  constantly  under  bell  jar 
from  rusted  seed.  Fig.  2. — Puccinia  vexans  Farl.  on  Bouteloua  racemosa,  both 
uredosori  and  amphisori  being  shown.  (Natural  size.)  Fig.  3. — The  same  ure- 
dosori  and  amphisori  shown  in  fig.  2  magnified  LO  diameters.  Fig.  4.  —  Uredo- 
spores  of  Puccinia  vexans  ■  600.  Fig.  5.  —  Amphispores  of  Puccinia  vexans  X  000. 
Fig.  6. — Teleutospore  of  Puccinia  vexans  ■  600.  Fig.  7.  Germinating  uredo; 
spore  of  Puccinia  vexans  ■  300.  Fig.  8.— Germinating  amphispores  of  Puccinia 
r,  cans  ■  300.  Fig.  9. —  Uredosori  of  Puccinia  vexans  on  young  seedling  leaf  of 
Bouteloua  racemosa  produced  by  artificial  infection  with  uredospores  from  t lie 
same  host,      i  Natural  size  I. 

32 

o 


Bui  63.  Bureau  of  Plant  Industry,  U  S  Dept  of  Agriculture. 


Plate  II. 


Rusts  of  Euphorbia  and  Grama  Grass. 


[Continued  from  page  2  o(  cover.] 

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54.  Persian  Gull  Pates.     1903.     Price,  m  cuts. 

The  Dry  Pot  of  Potatoes  Due  to   Fusarium  Oxysporum.     1904.     Price,  10 

cents. 

r>i>.  Nomenclature  of  the  Apple.     [In  press.] 

57.   Methods  Used  for  Controlling  and  Reclaiming  Sand  Dunes.     1904.     Price,  id 
cents 

The  Vitality  and  Germination  of  Seeds.     1904.     Price,  10  cents, 
59.  Pasture,  Meadow,  and  Forage  Crops  in  Nebraska.     1904.     Price,  10  cents. 
tin.   A  Soi't  Pot  oi  the  Calla  Lily.     [In  press.] 

«il.   The  Avocado.      [  In  press.  ] 

62.  Notes  on  Egyptian  Agriculture.     [In  press.  ] 


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